In the past, wooden beams referred to as studs have been used as the top and bottom beams of a building frame assembly and more recently sheet metal beams or studs have been provided for this purpose.
There are thermal insulation problems inherently associated with steel or sheet metal beams. Steel or sheet metal beams in frames produce a thermal bridge between either side of a wall frame, joist, or truss member or like metal structural components. This thermal bridging readily transfers heat across metal members, which results in excessive heating/cooling costs, condensation, and accelerated thermal rot in sheeting materials like drywall and siding. Heat transfer utilizes three basic mechanisms; conduction, radiation, and convection. With typical wood framing, the wood itself is an insulator, which eliminates conduction. Effective thermal sheeting and batten insulation prevent radiation across the frame and convection within the dead space. With steel sheet metal framing, the metal conducts heat across the frame. Sheeting and batten insulation reduce radiation and convection, but no satisfactory means has been provided to prevent conduction. Several approaches to reducing conduction involved reducing the amount of material in the web of a sheet metal beam, but no method to completely eliminate conduction in a sheet metal beam has heretofore been provided.
The patents to Farmer U.S. Pat. No. 4,071,995, Larsen U.S. Pat. No. 4,691,493 and Marschak U.S. Pat. No. 5,117,602 are directed to metal beams fabricated from roll-formed beam half sections but none teach a heat insulating layer interposed between the metal of opposite beam half sections.
Blomstedt U.S. Pat. No. 4,016,700, Rutkowski U.S. Pat. No. 4,435,936, Taylor U.S. Pat. Nos. 4,619,098 and 4,638,615 and Gilmour U.S. Pat. No. 5,285,615 relate to metal beams but have a thermal reduction feature such as slits, dimples or protuberances.